Add input validation and clarify sorted array requirement in Binary Search

[SwaatiR]

This PR adds a null and empty input check to the Binary Search implementation
to prevent invalid access and improves the JavaDoc to clearly state that the
algorithm requires a sorted array.

No changes were made to the core algorithm logic.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79.05%. Comparing base (48f6322) to head (479245b).

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/searches/BinarySearch.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7216      +/-   ##
============================================
- Coverage     79.05%   79.05%   -0.01%     
- Complexity     6945     6946       +1     
============================================
  Files           779      779              
  Lines         22906    22908       +2     
  Branches       4502     4502              
============================================
+ Hits          18109    18110       +1     
  Misses         4077     4077              
- Partials        720      721       +1     

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